Electrical control system



Dec. 21, 1954 G. E. UNDY 2,697,823

ELECTRICAL CONTROL SYSTEM Filed May 26, 1948 INVENTOR. wz av I &rza z4 I BY w age/g.

United States Patent ELECTRICAL CONTROL SYSTEM Gustav E. Undy, Detroit, Mich., assignor to Multi-Products C0., Hazel Park, Mich., a corporation of Michigan Application May 26, 1948, Serial No. 29,320 4 Claims. Cl. 340-147 This invention relates generally to method and apparatus for remotely controlling devices and more especially to those types of methods and apparatus in which a signal of particular characteristic is generated by a controllable radio transmitter and received by a receiver at a fixed location which is adapted when energized by a signal having the desired characteristics to operate a mechanism such as operating the doors of a vehicle garage entirely from within the vehicle.

An object of this invention is to provide a new method of remotely controlling a device.

A further object of this invention is to provide a novel and simplified coded controlling system which is economical to produce and trouble free in operation.

A further object of the invention is to provide such a system in which only the garage door actuated by a receiver which is tuned for receiving the particular type of signal transmitted by the transmitter will be actuated.

A further object of this invention is to provide in such a selective system a combination which will seldom if everbe transmitted due to interference signals set up in ether.

A still further object is to provide such a system in which the selection is accomplished by transmitting a predetermined sequence of pulses for operating the receiver mechanism.

A still further object of the invention is to provide such an impulse operated system which may easily be changed for operation with a different sequence.

A still further object of the invention is to provide such a system which will automatically reset itself to its initial position upon being actuated by its own actuating mechanism or partially actuated by any interference sig nals which may be present about the receiver so that the receiver is maintained responsive to a single set of signa s.

A still further object is to provide new apparatus for use in such a system.

Other objects will be apparent from the drawing, specification, and the hereinafter appended claims.

In the figure of the drawing, there is diagrammatically shown an illustrative circuit embodying the invention. Such circuit is to be construed as illustrating rather than limiting the scope of the invention which scope is to be determined solely by the hereinafter appended claims.

In the drawing, the numeral 1 designates generally a radio transmitter which may be associated with a motor vehicle (not shown) and energized from the battery B of the motor vehicle. 2 designates generally a radio receiver which may be energized from a transformer T1 having its primary winding 4 energized from a conventional 110 volt 60 cycle alternating current source. Brief- 1 stated, the transmitter 1 is energized upon closure of tile switch SW which energizes an electric motor 6 for operation by the battery B whereby an impulsing disk 8 is rotated. The rotation of the disk 8 causes a series of spaced impulses to be transmitted by an antenna 10 carried by the motor vehicle. The impulses from the antenna 10 are picked up by a receiving antenna 12 associated with the receiver 2, the impulses actuate a stepping relay SR,- which in turn actuates a selector switch SS. When the switch SS is properly positioned, a relay RLI will be energized causing the garage door mechanism to be operated. The specific structure for controlling the garage door mechanism is not illustratedbut may be of any suitable type, a number of which are known and commercially available,

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The transmitter 1 comprises a thermionictube 20 which may be of the type known to the trade as the 6SN7 type having within one envelope two triode valves. One of these valves 20a is connected in a network to oscillate and is tuned by means of a piezoelectric crystal 21 so that it is operable to generate a signal which may be in the order of 9 megacycles. by means of the condenser C1 and resistor R1 to the controlling grid of a frequency multiplying thermionic valve 22. The output of the valve 22 is fed through an antenna transformer T2 to the antenna 10. The other valve 20]) of the tube 20 is connected in a usual network as a regenerative-type oscillator and provides a signal of, for example, 10 kilocycles which signal is applied to the other grid of the valve 22 so that the transmitted signal is transmitted on the carrier wave generated by valve 22 modulated by the signal of valve 20b.

The anode circuits of the networks of the valves 20 and 22 are energized from a transformer T4, .the primary energization of the primary winding which is controlled by means of the impulsing disk 8. One terminal 23a of the battery B is connected to the vehicle frame which serves as the ground connection in the conventional man: net, the other terminal 23b is connected to one terminal 6a of the motor 6. The other terminal 6b of the motor 6 is connected through the normally open switch SW to ground and also through a slidable contact 24 which rests against the impulsing disk 8. The disk 8 is preferably fabricated of brass or other conducting material and is connected to ground by a conductor 26, the connection between the conductor 26 and disk 8 can be of any type but preferably is through a brush 28 which en gages a side face of the disk 8. The disk 8 is further provided with an insulating portion 30 which when the disk 8 is in its normal or zero position will underlie the brush 24 whereby circuit from the motor 6 to the disk 8 is broken. The terminal 23b of the battery B is also connected through the primary winding of the transformer T4 through a current limiting resistor R2 to a contact making finger 32. The disk 8 is provided with a series of contacts 34 which, upon rotation of the disk 8, will sequentially and periodically engage the contact finger 32 to complete a circuit from the battery B through the primary of the transformer T4, the resistor R2, the finger 32, contacts 34, the disk 8, brush 28, and conductor 26 to ground and thence through the ground to the other terminal 23a of the battery B.

Upon closure of the switch SW, the motor is energized thereby driving the disk 8 through the gear reduction 33. As the disk 8 rotates, the insulated segment 30 will move away from under the brush 24 so that the brush 24 Will engage the conduction portion of the disk 8 thereby completing a circuit in by-pass arrangement with respect to the switch SW which now may be opened without affecting subsequent operation of the transmitter 1. Preferably the insulation 30 is made small so that very little rotation of the disk 8 will be required to complete this by-pass circuit around the switch SW. The energized motor will now continue to turn the disk 8 at a predetermined rate whereby the contacts 34 will sequentially engage the finger 32 for keying the transmitter and energizing the transformer T4 at predeter mined spaced intervals. As the first of the contacts 34 engages the finger 32, the transformer T4 will be energized thereby energizing the anode circuits of each J of the valves 20 and 22, the valve 20a asrbefore described will then generate a signal in the magnitude of 9 megacycles which signal will be multiplied in the multiplier" valve 22 and transmitted to the antenna 10 through the transformer T2. At the same time, the valve portion 3 20b will generate a 10 kilocycle signal which also is transmitted to the frequency multiplying tube 22 whereby the output signal of the tube 22 will be proportional to the output of the signal of the valve 20a and which .signal will be modulated by the signal generated by the valve 2011.

lowed by two more spaced signals having the spacing This signal is transmitted substantially equal to the spacing of the original three signals.

The signal transmitted by the antenna 10 is picked up by the receiving antenna-12 and applied to an intermediate tap 36 of an antenna transformer 38 which is coupled through a detector network 41 to the controlling grid of a detector tube 40 which may be and preferably is of the type known as the 6517. The tube 40 is energized by the transformer T1 through a full wave rectifying tube 42 which supplies buses 44 and 46 with positive and negative potentials respectively. It will be noted that ground potential will be somewhat above that of the negative bus 46 since the ground 48 is connected to the bus 46 through a resistor R4.

The detector network comprises a capacitive-inductive network 50 tuned to be responsive to the kilocycle frequency with which the transmitted wave is modulated. A conductor 51 connects the network 50 with the grid of an amplifier valve 52 which grid will be biased with respect to the cathode of valve 52 in accordance with the strength of the received signal. The output signal of the valve 40 thus amplified by the valve 52 is fed into the primary winding of a transformer T5, the secondary winding of which is connected between the grid of one valve section 54a of a thermionic tube 54 of the type known to the trade as the 6SN7 and ground through a condenser C5. A resistor R5 connects the terminal of this secondary winding, which is grounded through condenser C5, to the negative bus 46 whereby with no signal being supplied by the valve 52 the conductivity of the valve section 540 will be held to a low. value. The anode of the valve portion 54a is connected by means of a conductor 56 to one terminal of the energizing winding of the stepping relay SR while the cathode is connected to ground. The other terminal of the energizing winding of this relay is connected directly to the bus 44. Normally the bias on the grid is such that insuflicient current will flow through the winding of the relay SR to actuate the relay. However, when a signal of the proper characteristic is received by the antenna 12 and fed to the detector valve 40, the amplified output of the valve 52 will change the bias on the grid of the valve section 54a whereby sufiicient current will be passed through this valve section to actuate the relay SR. 7

The valve section 54b of the thermionic tube 54 has its grid connected to ground through a resistor R6 and has its cathode connectible to ground through the switch SW1 and connected to the positive bus 44 through the resistor R7. A condenser C3 connects the grid to the cathode for a purpose to be set forth below. It will be apparent that with the switch SW1 in its open position as shown, the grid of the valve portion 54b will be biased negatively with respect to its cathode whereby conduction through the valve portion 54b will be held to a minimum. The anode of the valve portion 54b is connected by means of conductor 58 through normally closed contacts SRa of the relay SR to the conductor 56. Actuation of the relay SR moves the pawl 60 thereof downwardly to rotate the ratchet wheel 62 of the stepping relay one step whereby the movable contact 64 of the stepping switch SS will move clockwise from one of the contacts 66 to the next adjacent contact. Subsequent de-energization of the relay SR permits the spring 68 to return the pawl 60. Subsequent actuations of the relay SR cause the pawl 60 to be moved down and back thereby moving the movable arm 64 to engage sequential ones of the contacts 66. Also driven by the ratchet 62 is a cam wheel 70 for actuating the switching device SW1 the cam 70 is so chosen that the switch SW1 will be in closed position at all positions of the movable arm 64 except the position in which the contact arm 64 is in engagement with the zero one of the contacts 66.

'The stepping switch SS comprises a disk upon which are mounted a series of equally spaced contacts 66 for convenience sub-numbered in the presentinstance -1-1 to correspond with twelve teeth of the ratchet wheel 62. connections being made therefrom corresponding tothe location of the contacts 34 of the transmitter impulsing disk 8. In this instance contacts 3 and of the contacts 66 are utilized to render the receiver 2 responsive to the 3--2 signal transmitted by the shown transmitter 1 in .a manner which will be brought out below. The

Most of the contacts 66 are unconnected,

sistor. R8 to the bus 44. The movable arm 64 is con-- nected to one terminal 72 of a condenser C9, the other terminal of which is connected to the bus 46 whereby upon contact being made by the arm 64 with the contact 3 of the contacts 66 a charge will be applied to the condenser C9. The resistor R8 acts to control the rate at which the condenser C9 is charged for a pur pose to be made clear hereinafter. The contact 5 of the contacts 66 is connected through the energizing winding of a relay RLl to the other terminal of the condenser C9 whereby when the arm 64 is in contact making position with the contact 5 of the contacts 66 the condenser is connected to discharge therethrough. A resistor R11 is connected in series with the winding of the relay DLl while a condenser C11 is connected directly across this winding for the purpose of imparting a time delay betwen completion of this discharge circuit and actuation of the relay RLl to close its contacts RLla, the purpose of which will be made clear below.

The condenser C9 in this instance is of the electrolytic type and such condensers for best performance are maintained in condition by continually subjecting them to a partial charge. For this purpose a voltage divider 74 is provided, the divider 74 comprising a first resistor R9, one terminal of which is connected to the bus 46 and a second resistor R10, one terminal of which is connected to the bus 44. The'other terminals of the resistors R9 and R10 are connected together to provide an intermediate voltage point or tap which is connected to the terminal 72 of the condenser C9 associated with the arm 64 whereby a minimum voltage across the condenser C9 is continually provided.

In the receiver shown, a relay RL2 is shown as hav ing its energizing Winding connected in series with a resistor R12 and the contact 6 of the contacts 66 across the condenser C9. This relay RL2 would not be actuated by the shown transmitter 1 and illustrates the manner in which a single receiver can respond to two different transmitters 1 having different code combinations for operating each of two different mechanisms depending upon the transmitted code. The code for therelay RL2 would be'3-3.

It is believed that the remainder of the construction may best be understood by a description of the operation of this invention which is as follows:

When itis desired to' actuate the garage door from the motor vehicle, the operator of the vehicle closes the switch Sw which completes a circuit, as above described, from the battery B through the motor 6 whereby the motor starts to rotate causing the insulating portion 30 to be moved out from under the brush 24 for completing a holding circuit for continued actuation of the motor 6 after which the switch Sw is released. The pulsing disk 8 continues to be rotated by the motor 6 for a complete revolution at which time the insulating portion will again underlie the brush 24 and break the circuit. The contacts 34 of the impulsing disk 8 upon rotation of the disk 8 sequentially engage the wiping contact 32 thereby providing a series energization of the transformer T4 through a circuit from the battery B through the primary of the transformer T4 through the finger 32 and contacts 34 and back to the battery through the conductor 26 and the ground connections. It should be here noted that the contacts 34 are arranged in two groups of substantially equally spaced contacts, the particular arrangement illustrated being 32, for a purpose which will be made clear hereinafter. As the various contacts 34 make connection with the finger 32, the secondary winding of the transformer T4 will supply a pulse of voltage to the anode circuit of the oscillating networks associated with the valve portions 20a and 20b and to the valve 22. Upon being so supplied with anode voltage, the oscillating network associated with the valve portion 20a will impress an oscillating signal upon the grid of the valve 22 and at the same time the valve portion 20b will impress a modulating wave upon this output signal whereby the modulated signal will be impressed upon the grid of the valve 22 causing current to flow therethrough energizing the transmitting transformer T2 for impressing a signal upon the transmitting antenna 10 carried by the motor vehicle.

. This signal is picked up by the receiving antenna 12 and impressed upon the grid of the detector valve 40 whereby a signal is impressed upon the grid of the valve 52, amplified therein, and the amplified signal impressed upon the transformer T5. Upon energization of the transformer T5, the bias of the grid of the valve portion 54a will be altered so that the valve portion 54a will conduct sufficient current from the bus 44 through the energizing winding of the relay SR, the conductor 56, the valve portion 54a, the grounded cathode thereof, the ground connection 48,.the resistor R4 back to the negative bus 4-6 whereby the relay SR will be actuated moving the pawl 60 downwardly to rotate the movable brush arm 64 from the zero position to the number 1 position and also moving the cam 70 to close the contacts of the switch SW1. The duration of this signal is short and almost immediately the relay SR is de-energized whereby the spring 68 pulls the pawl 60 upwardly to its original position whereby it is ready, upon subsequent energization of the relay SR, to again move the ratchet wheel 62 one notch and the brush arm 64 to the next of the contacts 66.

Immediately upon closure of the switch SW1, the potential of the cathode of the valve portion 5412 was lowered to ground potential. Since, however, a finite time is required for a condenser to discharge, the condenser C3 which is connected between the grid and cathode of the valve portion 541) will not immediately discharge but because of its charge will act to lower the potential of the grid of the valve 54b and continue to maintain the grid negative with respect to the cathode until such time as the charge on the condenser C3 leaks off through the resistor R6. The time characteristic of the condenser C3 and of resistor R6 is so chosen that this charge on the condenser C3 will not leak oif until completion of the operating cycle of the disk 8 of the transmitter 1. Therefore the valve portion 54b will be biased to a minimum flow condition during operation of the transmitter 1 and the operation of the switch SW1 is Without immediate effect to cause current to flow even though the contacts SRa may be subsequently closed and opened during the time period that the transmitter 1 is going through its cycle,

Upon closure of a circuit between the first one of the contacts 34 and the finger 32, the relay SR will be energized moving the movable arm 64 from the 0 contact of the contacts 66 to the contact 1 thereof without effect. As the impulsing disk 8 continues to rotate, the second and third ones of the contacts 34 will engage the arm 32 whereby the brush 64 will be moved into contact-making position with the second and the third contacts of the contacts 66 of the stepping switch SS. It will be noted that the third contact of the contacts 66 of the stepping switch SS is connected to the bus 44 through a resistor R8 while the movable arm 64 is connected to the terminal 72 of the condenser C9. The condenser C9 will increase in charge under control of the resistor R8 and after a predetermined interval will have obtained a predetermined charge of suflicient magnitude so that when the condenser C9 is connected across the winding of the relay RL1, it will be suflicient to actuate the relay RLl. The space between the third and fourth contacts of the impulse disk 8 is greater than the spacing of any of the other contacts 34 and is so chosen relative to the speed of drive of the impulsing disk 8 by the motor 6 that the movable arm 64 is maintained in engagement with the contact 3 of the contacts 66 a sufiicient time period to permit the condenser C9 to obtain its predetermined charge so that at the proper time, it will actuate the relay RLl.

After the condenser C9 has received this predetermined charge, the fourth contact 34 of the impulsing disk 8 will engage the finger 32 causing the stepping relay SR to move the ratchet wheel 62 another notch whereby the wiping arm 64 will move into engagement with contact 4 of the contacts 66. Subsequent engagement of the fifth of the contacts 34 of the impulsing disk 8 with the finger 32 will cause the stepping relay to again be energized moving the wiper arm 64 into engagement with contact 5 of the contacts 66. It will be noted that contact 5 of the contacts 66 is connected to the actuating winding of the relay RLl so that after a predetermined time interval depending upon the relative value of an energizable delaying mechanism comprising the resistor R11 and condenser C11, the relay RLl will be actuated to close its contacts RLla. The value of the condenser C11 and resistor R11 is so chosen that the time imparted to delay the actuation of the relay RLl is greater than the time interval between engagement of successive ones 6. of the contacts 34 with the wiper 32 so that were disk 8 to contain another contact 34 another operation of the relay SR would occur causing the arm 64 to pass on to the next one of the contacts 66 and the relay RLl would not be operated. In the particular coded arrangement shown, the arm 64 will remain in engagement with the contact 5 of the contacts 66 longer than the time period of the condenser C11 and resistor R11 and the relay RLl will actuate closing its contacts RLla. Closure of the contacts RLla initiates a set of operations whereby the door is either opened or closed depending upon the position in which it was in at the time the relay RLl was actuated.

Subsequent to completion of a complete revolution of the disk 8, the condenser C3 will time out so that the bias on the grid of the valve portion 54b will have leaked off through the resistor R6 and the valve portion 54b will commence to conduct, again energizing the relay SR causing the ratchet wheel 62 to be rotated a further space and the contact arm 64 to be rotated to the next one of the contacts 66. In order to insure continued energization of the relay SR for it to complete its movement of the arm 64 to the next contact after opening of the contacts SRa, a condenser C14 is positioned in shunt relation with the contacts SRa. As soon as the ratchet wheel 62 has been moved to its next position, the con denser C14 will have been discharged. The spring 68 will move the relay SR back to its original position closing the contacts SRa and initiating a subsequent cycle to cause the ratchet wheel to be moved another notch and the arm 64 to be moved to the next subsequent one of the contacts 66. This stepping operation will continue until such time as the arm 64 reaches the zero one of the contacts 66 at which time the switch SW1 will be opened throwing a positive potential upon the cathode of the valve 54b from the bus 44 through the resistor R7, thereby reducing current flow through the valve portion 54b to a value insuificient to again actuate the relay SR and the switch SS will be left in its reset position for a subsequent operation of the transmitter 1.

Now consider the effect of an improper signal being received say a 4-1 signal such as would be transmitted with four equally spaced contacts 34 a space and then one contact 34. The switch SS would be stepped four times instead of the described three in substantially the manner described above. contact 3 of the contacts 66, the condenser C9 would start to charge. As described above, the finite time is required to provide the condenser C9 with a sufficient charge to operate the relay RLI and this time interval is greater than the time interval between successive contact engagements of the first set of contacts 34 with the finger 32 and consequently the switch SS will have its arm 64 moved away from contact 3 of the contacts 66 prior to the condenser C9 receiving a suificient charge for actuation of the relay RLl. Therefore, even though the arm is brought into engagement with contact 5 upon movement of the last contact 34 into circuit making ongagement with the finger 32 and remains in this condition until the resetting operation begins the relay RLI cannot be actuated.

The spacing of the second group of contacts 34 is similar to the spacing of the first group in that the time be tween successive engagement thereof with the finger will be less than that required to impress the predetermined charge on the condenser C9. For example a 23 code Wiil not charge the condenser-C9 the required amount.

Suppose now that the transmitter was coded 34. The condenser C9 would be charged as described above in connection with the 32 code. As the second set of contacts 34 stepped the switch SS to contact 5 of the contacts 66, the charge on the condenser C9 would start to flow to the circuit containing the relay RLl. The presence of the resistor R11 and condenser C11 however delays the actuation of the relay until the condenser C11 is suitably charged to permit a critical operating potential to appear across the terminals of the energizing winding of the relay RLl. This interval of charging of the con-v denser C11 is greater than the time interval between successive engagements of the contacts 34 with the finger 32 and the relay RLI will not be actuated.

Likewise the time interval durin which the brush arm 64 engages any one of the contacts 66 during resetting operation is less than the time required either to charge the condenser C9 sufiiciently for operating a relay RLl or As the arm 64 contacted the R132 and less than the time required for the actuation of eitherof these relays should the condenser C9 have been sufficientlypcharged. It should be noted thatthe time interyal Iprovided by the resetting timeout condenser C3 is sufiicient so thatif the condenser C9 does not discharge through a relay RL1 or RLZ the charge will leak otf through the resistor R9 so that for each new operation of the switch SS from its reset position the condenser C9 is initially at the charge determined by the relative values of the resistors R9 and R10.

It is therfore now evident that to charge the condenser C9 for operation of the relay RL1, the same number of contacts 34 must be provided as the number of the contacts 66 to which the resistor R8 is connected and that to utilize the proper charge on the condenser C9 requires a longer time period than that between successive engagements of the'cont'acts 34 with the finger 32. Therefore the first group of contacts 34 must correspond in number to the number of contacts from the reset position to the charging position of switch SS and the second group of contacts 34 must equal the number of contacts 66 from the charging contact to' the contact connected to the desired relay for actuating the controlled device.

If it is now desired to have two doors open selectively by the same receiver, another of the contacts 66 for example, contact 6, may be connected through a resistor R12 to one terminal of the energizing winding RL2, the other terminal of which is connected to the conductor 46. A condenser C12 is provided in shunt relation with the energizing winding of the relay RL2. and acts as a time delay means as does the condenser C11 associated with the relay RLl. In this event a transmitter having a signal of three initial impulses is necessary in order for the condenser C9 to be properly charged to actuate the relay RLZ and a second or following group of 3 impulses is necessary for the relay RL2 to be actuated to thereby control the garage door or other mechanism which is connected to be operated by the relay RL2.

What is claimed and is desired to be secured by United States Letters Patent is as follows:

1. In combination, a transmitter, means controlling the output of said transmitter and including a rotatable modulating member, means for rotating said member one complete revolution in a predetermined time interval, said output controlling means being actuated as a consequence of the rotation of said member to cause said transmitter to transmit at least one signal pulse, a receiver'connected to receive said pulse and having an output circuit, a switching device having a pair of contacts and connected to said output circuit to close said contacts as a consequence of said receiver receiving a predetermined number of said pulses, a control device, an energizable delaying mechanism, circuit means energized as a consequence of closure of said contacts and including said control device and said delaying mechanism, said delaying mechanism being operable to delay the actuation of said control device for a predetermined time interval subsequent to closure of said contacts and rendered effective to measure out said time interval as a consequence of the energization of said circuit means whereby said control device is actuated solely when said circuit means is energized for a a time interval not less than said predetermined interval, means for returning said switching device to an initial position, and timing means rendered eflective as a consequence of the energization of said output circuit for actuating said return means to return said switching device to said initial position, said timing means having a time factor at least equal to the time required to rotate said rotatable modulating member one revolution, and means for disabling said timing means when said switching means returns to said initial position, whereby said timing means is effective to actuate said return means solely at the end of a predetermined time interval measured from the time said output circuit is energized.

2. A controlling system comprising, a sending means for generating an output signal of predetermined duration and which is impressed with a predetermined modulation, a receiving means actuatable by modulated variations of said output signal, said sending means including a rotary switching actuator for controlling the duration and the modulated variations of said output signal, said receiving means including an energy storage element having a charging circuit and a discharging circuit and means for controlling the rate of charging and discharging said element, a control device connected to the discharging circuit,

rotary step-switching apparatus incorporated in said receiving means and actuatable as a consequence 'of successive va'riations J of said sig'iialto successively'con'nect said storage element to said charging circuit and then to said discharging circuit, said sending means actuator acting to provide a different time interval between variations of said output signal which actuate said step-switching apparatus to connect and then disconnect said storage element with respect to said charging circuit and successive said variations which actuate said step-switching ap paratus to and from successive positions, said step-switching apparatus being normally rotated to the completion of a rotary travel until it reaches and is maintained in an initial position, and supplemental actuating means for said step-switching means to continue rotation thereof to return said controlling apparatus to said initial position, said last-named means including a time delay means rendered efiective as a consequence of one of said variations to delay said return for a period exceeding the full duration of said signal.

3. In a remote control selective system, the combination of a sender and a receiver, said sender comprising automatic cyclic keying means for sending a first group of equally spaced signal pulses and a second group of equally spaced signal pulses spaced from said first group by a time interval greater than the time interval between the pulses of either of said groups, said receiver comprising a continuously rotatable step-switch mechanism, means for actuating said switch mechanism in steps corresponding to and in response to said pulses, an energy storage device having a charging circuit which includes said step-switch mechanism, said charging circuit also including timing means for timing the rate of charging of said storage device, said step-switch mechanism being operable upon being stepped a number of times corresponding to the number of said pulses of said first group to connect said charging circuit to a source of electrical energy, said timing means having a time constant such that the time required to charge said storage device to a predetermined minimum charge from said source is greater than the'time interval between said successive pulses of either of said groups but not greater than said time interval between said groups, a control device, an energizing circuit for said control device including said step-switch mechanism and said storage device and further including timing means having a timing cycle longer than the time period between said pulses for controlling the interval between the time said energizing circuit is energized and the time said control device is actuated, said step-switch mechanism being operable upon being stepped a total number of times corresponding to the total number of all of said pulses for connecting said storage device to discharge through said control device, said storage device being etfective to actuate said control device solely subsequent to said storage device having previously received said predetermined charge.

4. In a remote control selective system, the combination of a sender and a receiver, said sender comprising rotary keying switch means for sending a first group of equally spaced signal pulses and a second group of equally spaced signal pulses spaced from said first group by a time interval greater than the time interval between the pulses of either of said groups, each said group comprislng a predetermined fixed number of pulses, said receiver comprising a continuously rotatable step-switch mechanlsm, means for actuating said switch mechanism in steps corresponding to and in response to said pulses and having at least as many steps as the total number of said pulses of each said group, an energy storage device having a charging circuit which includes said step-switch mechanism, said step-switch mechanism including a circuit closing device which is closed to energize said circuit as a consequence of said mechanism being stepped by said first group predetermined number of pulses, and said chargmg circuit including means for timing the rate of charging of said storage device, said timing means having a time constant such that the time required to charge said storage devlce to a predetermined minimum charge is greater than the time interval between said successive pulses of sald first group but not greater than said time interval between said groups, a control device, an energizing circult for said control device including said step-switch mechanism and said storage device, and further timing means for controlling the time period between the time said energizing circuit is energized and the time said control device is actuated, said step-switch mechanism including a second circuit closing device which is closed to energize said last-named circuit as a consequence of said mechanism being stepped by the total number of said pulses of both said groups, said storage device acting as the source of energy for said control device and efiective to actuate said control device solely subsequent to said storage device having received said predetermined charge, and said timing means having a time cycle longer than that required for one full rotation of said keying switch.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,455,099 Baker May 15, 1923 1,760,479 Colman May 27, 1930 Number 10 Name Date Fitzgerald May 12, 1931 Beverage Sept. 17, 1935 Boyajian Nov. 6, 1945 Dinga Apr. 2, 1946 Deal et a1. Dec. 31, 1946 Davis Apr. 20, 15/48 Hansen May 11, 1948 Oliver Oct. 19, 1948 Schirokauer Mar. 1, 1949 Desch et a1 Apr. 12, 1949 Barnard et a1 Aug. 30, 1949 Garber Oct. 4, 1949 

